Final answer:
Carbapenems are not typically effective against atypical bacteria due to their unique cell wall structure. Instead, antibiotics like macrolides or tetracyclines are used. The emergence of carbapenem-resistant Enterobacteriaceae (CRE) requires lab tests to guide effective treatment.
Step-by-step explanation:
Carbapenems are broad-spectrum antibiotics that are highly effective against a wide range of bacteria, including both gram-positive and gram-negative species. However, their efficacy against atypical bacteria, which include Mycoplasma, Chlamydia, and Legionella species, is often limited because these organisms have unique characteristics such as the lack of a traditional cell wall, which is the target of the ß-lactam ring present in carbapenems. Atypical bacteria are usually treated with antibiotics other than ß-lactam antibiotics, such as macrolides or tetracyclines. The development of carbapenem-resistant Enterobacteriaceae (CRE), often mediated by enzymes like carbapenemases, poses a significant challenge in treating infections. Lab tests for carbapenemase production and antimicrobial susceptibility profiles guide clinicians in selecting effective therapies against these resistant strains.